Cochlear implants may provide a person having sensorineural hearing loss with the ability to perceive sound by stimulating the person's auditory nerve via an array of electrodes implanted in the person's cochlea. An external component of the cochlear implant detects sound waves, which are converted into a series of electrical impulses delivered to the implant recipient's auditory nerve via the array of electrodes. Stimulating the auditory nerve in this manner may enable the cochlear implant recipient's brain to perceive a hearing sensation that is similar to the natural hearing sensation delivered to the auditory nerve.
One problem with cochlear implants is that the electrodes can sometimes stimulate more than just the cochlear implant recipient's auditory nerve. The implant recipient may not always recognize non-auditory nerve stimulations, or may not be able to indicate reliably (as in the case of small children or mentally disabled recipients), but over time, non-auditory nerve stimulations can be annoying or even painful to the implant recipient. The most common non-auditory nerve stimulation is stimulation of the facial nerve.
Typically, when a cochlear implant is being surgically implanted into a recipient, external sensors applied to the surface of the recipient's skin are used to detect facial nerve impulses. Facial nerve impulses are large and fairly easy to detect with external sensors. These external sensors let the surgeon know when the facial nerve is touched during the surgery where the cochlear implant is being implanted into the recipient.
After the cochlear implant has been implanted into the recipient, an audiologist or other similarly-trained specialist may fine-tune the settings of the cochlear implant. Sometimes, the implant recipient may even fine-tune certain settings of the cochlear implant themselves. This post-operative fine-tuning process is known as “fitting” the implant to the recipient. During the fitting process, the audiologist or the recipient may adjust the cochlear implant settings in a way that causes the cochlear implant to stimulate the facial nerve. And because the recipient may not always be able to initially recognize the facial nerve stimulation, or because the recipient may not always be able to give reliable feedback, the resulting implant configuration may cause facial nerve stimulation.